Gastric ring systems of the type comprising an outer chamber and an inner balloon arranged in a physiological liquid contained in the space between the chamber and the balloon are known. A greater or lesser inflation of the balloon increases or reduces the diameter of the gastric ring. The adaptation of the inflation is carried out with the aid of a syringe with which the practicing physician sends a physiological liquid via a reception chamber arranged under an incision in the skin of the patient, and a tube leading to the ring. The disadvantages of such solutions can be imagined: Pain at the level of the permanently arranged chamber, risk of leaks, abuses of manipulations requested on certain occasions by the patients, etc., risk of infection.
Motorized gastric ring apparatus has been developed whose control is carried out by remote control without having recourse to incisions, streams of physiological liquid, reception chamber, tubes, etc.
In particular, FR 2 816 828, EP 0015140 and FR 2 797 181 are known. Those systems essentially comprise a not entirely closed ring intended to be placed around the esophagus, which ring comprises an internal band fixed to one of the ring ends and exiting from the ring by its other end, which band can slide in the ring under the action of a micromotorization (traction system) arranged in a distinct element comprising the motorization, and integrated electronics (electronics for saving energy, processing command signals, supplying the micromotorization, sending command signals to the motorization, managing memories and memory data, updating the data, and other functions of this type).
One skilled in the art will understand that by exerting a traction on the band the ring is tightened around the esophagus and inversely if the traction is loosened. These various apparatus are of great importance.
However, a significant problem is posed in the sense that the gastric ring can move after it has been positioned and finally come to rest on certain organs such as the liver or the stomach. It is necessary to define the following elements more precisely to define more accurately the movement which the AGM undergoes:                The AGM is constituted (FIG. 4) of a cylinder 2 containing a motor, electronics and receiving antenna, and the ring 1 placed around the esophagus is located in front of this cylinder. This ring, whose diameter can be increased or reduced, defines a plane whose orientation relative to the transmitting antenna is very important (FIG. 1).        
In fact, this orientation determines the quantity of energy received by the ring. Too small a quantity of energy received is expressed at first by a halt in the operation of the motor, then by a halt in the communication with the AGM. The antenna of the AGM versions of the prior art is placed in a standard manner at 90° from the plane formed by the ring.